PROJECT SUMMARY Youth violence in the United States is common and is associated with numerous adverse health, academic, and psychosocial outcomes. Programs aimed at preventing youth violence have shown only modest success. Consequently, researchers have begun exploring additional primary prevention strategies that can augment existing programs, including anti-bullying policies. Though all 50 states have enacted some type of anti-bullying legislation, there is a striking dearth of research on whether, why, and for whom these laws are effective in preventing bullying and other forms of youth violence. Pilot data from our research group has provided some of the first evidence of the impact of anti-bullying laws on bullying behaviors. While promising, these initial studies have several limitations, including a reliance on cross-sectional designs, a limited number of states, a narrow range of youth violence outcomes, and an examination of only one anti-bullying legal framework. Our proposed study addresses these limitations through pursuing three aims. First, we will use longitudinal and quasi- experimental data to evaluate the effectiveness of anti-bullying laws in reducing multiple forms of violent behaviors among youth, including bullying, cyberbullying, peer-to-peer fighting and assaults at school, and weapons carrying. We will also examine whether improved school climate mediates the prospective association between anti-bullying legislation and youth violence outcomes. Second, we will evaluate the effectiveness of anti-bullying policies in reducing group-based disparities (e.g., sex, weight, sexual orientation) in multiple forms of youth violence. To address these two aims, our team of legal experts will conduct the first longitudinal content analysis of anti-bullying laws (and amendments) from their inception in 1999 through 2017; these laws will be coded according to 3 legal frameworks. We will link this legal data to two datasets with student- and school-level reports of youth violence, including the Youth Risk Behavior Surveillance Surveys and the School Survey on Crime and Safety. Third, we will evaluate whether fidelity of implementation of anti-bullying laws impacts youth violence outcomes. To address this aim, we will collaborate with the Maine Department of Education to carry out two panel surveys with school administrators and school counselors to measure the fidelity of implementation of anti-bullying laws. These implementation data will be linked to youth violence outcomes from three data sources in Maine, which will include student reports from 5th-12th graders as well as school reports of substantiated bullying cases. This research is highly innovative in that it uses a multi-method, multi-measure, multi-level, multi- disciplinary approach to pursue these aims. This study will provide the most comprehensive, methodologically rigorous evaluation of anti-bullying legislation to date. Findings will provide actionable evidence for diverse actors, including legislators involved in amending anti-bullying laws; state and local agencies responsible for carrying out provisions of the laws; and students and families who are directly affected by the strategies implemented by their schools to adhere to the law.